1. Field of the Invention
The present invention relates to an apparatus for processing flushing liquor from a gas main of a coke oven to provide a watery liquid essentially free of tar and solid particles for continued use to flush such gas mains and to provide tar which is essentially free of solid particles and water.
2. Description of the Prior Art
In the production of coke from coal in coke ovens, gases are liberated from the coal. These gases are collected in a relatively large main that extends along the length of the coke oven battery and are subjected to aqueous sprays of a liquid known as flushing liquor.
The aqueous spray cools the gases and condenses the steam and tar portions of the gases. The tar is insoluble in water. Consequently, a two-phase liquid stream containing tar and aqueous flushing liquor is produced. The tar is a heavy, viscuous mixture of hydrocarbons having a specific gravity in a range of about 1.1 to 1.25. The solids, of course, are heavier. The flushing liquor is an aqueous solution containing ammonia, tar acids, such as phenol, and combined ammonia such as ammonium chloride.
The primary purpose of the decanter tank is to separate tar and flushing liquor by settling as the difference in density of the tar and flushing liquor permits; however, it must also remove the solid materials. The densities are such that water forms the upper layer, tar the lower layer, and the solids collect at the bottom of the vessel. The solid materials are undesirable in either the tar or the liquor fraction. The flushing liquor is recycled to the collector main for use in cooling further gases that are being produced during the coking operation.
The decanter tanks have heretofore been rectangular in shape, long and flat. This configuration has given ample settling time and area. However, recent changes in the coking industry due to expansion, government regulations, and increased energy prices have made such types of decantation equipment disadvantageous.